The features of the digital products are growing enormously which triggers the frequent usage of smart phones in several applications. Thus the battery backup time is getting decreased. It will be fun to build a Power Bank for Mobile Phone as spare charging source for emergency purpose which is also portable. In this article we will discover how to make a power bank with a super simple power bank circuit diagram.

The important factor to be considered while working with lithium batteries is protection circuits and quality of batteries. But, when this comes to 18650 cells the risk factor is less compared with pouch batteries. Good protection is offered by few readymade modules available in market.

Components required:

18650 Lithium cell

TP4056 Module with battery protection circuit

3V to 5V boost converter with 1A current control

Slide switch

Power Bank Circuit Diagram:

Below is the circuit diagram for our power bank. As we can see its fairly easy to make a power bank with li-ion battery, TP4056 module and a boost converter.

18650 Lithium Cell:

The term 18650 cell is due to the cell dimension, it is cylindrical in shape with 18mm diameter and height of 65mm. Also these cells are available in different capacities corresponding to applications. They are rechargeable cells with 3.7v output.

The method of charging a single lithium ion cell requires two stage,

Constant current (CC)

Constant voltage (CV)

During CC the charger should supply constant current with increasing voltage till the voltage limit. Next a voltage equal to maximum limit of cell should be applied during which the current declines steadily to the lower threshold current (i.e., 3% of constant current). All these operation is carried out by the TP4056 module which is highly reliable and affordable choice.

TP4056A Module:

This is a low cost charging solution to charge any type of single lithium ion battery. Mobile batteries, 18650 NMC cells, Lithium pouch batteries, etc. The micro B Receptacle and easy adjustable 1A output current control makes it reliable choice to charge any low capacity batteries. It can be connected to any wall socket based mobile charger or any sort of USB to micro B cable. It is made of an integrated PMOS load switch architecture, hence reducing overall additional components.

The module also has two indications, Red color LED (L1) to indicate the ongoing charging condition. Blue color LED (L2) indicates the completion of charging. This module can operate at high ambient temperature since the thermal feedback can regulate the charge current. The charge voltage is 4.2V and current can be adjusted by changing a resistor in the module. But, the default current will be 1A when bought.

2. FS8205A – Dual N-Channel enhancement MOSFET with common drain connection. Also the drain to source resistance is low. The gate of the MOSFET is controlled through the DW01A IC.

Thus, the DW01A provides Overcharge control, Over discharge control, Overcurrent control by controlling the MOSFET through the circuit.

Micro USB 3V to 5V Boost Converter:

Lithium battery is only providing 3.7 volt here but we need 5v to charge the Cellphone, so we have used 3v to 5v boost converter module here. This boost converter module has high efficiency of upto 92% and integrated over current protection. The topology used inside is Non-isolated step-up converter which operates at a switch frequency of 1MHz. The overall power output that can be drawn out of this module is 5W. The output voltage can be adjusted to 12V by changing a resistor in module but the maximum current will be 400mA. But by default this module is available at a rating of 5V, 1A. Under this rating the output ripple is 20mV pk-pk. The module also has USB type-A female receptacle which is universal. Any USB power cable can be used as interface. The operating temperature of the module is -40°C to +85°C. It also has an LED indication to indicate the presence of supply from battery source. The Red color Led indicates the presence of power supply across the terminals.

To increase capacity number of lithium cells can be increased in parallel.
When using the same module arrangement the charging time increases
equally to the capacity, Eg: 10000mAh takes about 10 hours to charge from
empty to full. But, there is no other problem in using in that way. Ensure the
cells that are connected in parallel are of same capacity (For eg : 3.6V, 2200mAh).

So there is no need to be worried about balance charging? and where would we be able to connect a higher input voltage if the batteries allowed for it, or would we just create a whole new circuit leading to the positive and negative ends of the batteries in parallel in order to charge at a higher voltage?

This module is designed to charge a 18650 cell whose full charge voltage is 4.2V. Also the charging current of these cells are rated less than 1A. So why do you need a 2A charger? A charging current of 2A or more could easily kill a 18650 cell..

There is no over-discharge protection. The booster is connected in parallel to the battery and TP4056, thus even if the TP module was powered on it would have no control over the discharge from the booster. To fix this you need a discharge protection IC in series with the booster and battery.

The circuit you give is different from the PCB. On the circuit you have the switch between the 2 pluses, on the PCB you have it between the 2 minuses. You do not give good explanations how to connect the switch and you do not show the connections well on the PCB pictures.

i don`t see a deep discharge protection. if it is the step-up booster i think it is.
It discharge your battery to almost a 0,5 volts lithium battery`s dont like that and wil posibley be dead or get dangerous after it, becouse the chemestry inside the battery wil get unstable. inside your phone te battery is monitored by a bms battery monitoring system en wil never !!!! be fulli dicharged.
so my 2 cents, get a undervoltage protection at a rc hobby shop for example.

The TP-4056 is meant to charge only one battery at a time. If you have connected the batteries in series and then have connected to the module, then you the voltage off all the three batteries would have added up and thus damaged your module

Thank you for the instructions. I made it. but the boost converter is heated when the mobile phone is charging.Is there any solution to reduce the heat. Or , does the guage of wires matter for this situation as the wires can't bear the current?